S. Hadwen 
335 
The time taken for the emergence of Hypoderma lineatum from 
the pupa. 
4 larvae found in a stable on 20. iii. 13, all emerged before 16 days. 
3 larvae squeezed out 21. iii. 13, emerged before 14 days. 
5 larvae squeezed out 21. iii. 13, all emerged before 19 days. 
1 larva found in a stable on day of emergence, 22. in. 13, hatched in 
13 days. 
These larvae were kept in an incubator with intermittent heat up 
to 32° C. This shows how the temperature will influence the early or 
late appearance of warble flies in the spring. A large number of larvae 
were secured during the spring of 1913 ; nearly all were of H. lineatum, 
H. bovis only appearing later. It was thought that in the spring of 
1914 H. lineatum would be plentiful, but the contrary has proved to 
be the case ; most of the larvae secured so far are of H. hovis. Possibly 
the season may be responsible for this, as the early spring of 1913 was 
very wet. No specimens of H. lineatum were captured out of doors, 
but H. bovis was caught at a later date. 
Observations made in 1914. 
H. lineatum. On May 15th a calf was observed to “ gad.” No 
warble flies were seen on this date, and the other animals in the field 
showed no uneasiness. Tabanus affinis Kirby appeared on the same 
day. 
Since no warble flies had been seen as early as this in previous years, 
it was thought that the calf might be extra sensitive and that the 
Tabanidae were responsible for his fright. However three days later. 
May 18th, a H. lineatum $ was captured in the following peculiar 
manner ; the farm herdsman noticed that a bull which he had tethered 
outside the barn was tossing his head in a strange way ; the animal 
was lying down at the time. On approaching he saw a fly on its breast 
and killed it by slapping it with his hand. At this moment I happened 
to be passing, and the herdsman handed me the fly, which I perceived 
at once to be a H. lineatum $ . He told me that the fly appeared to be 
stuck to the bull when he first saw it. All this time the bull remained 
quite quiet and displayed no uneasiness. This observation is recorded 
to show how little fear this fly may engender as compared to H. bovis. 
Later in the season similar observations were made. On May 29th 
two specimens of H. lineatum were captured. On this occasion one was 
seen ovipositing on a cow’s foot, just under the dew-claws ; a search 
